When you use the date dropdown to look at weekly, monthly or other date ranges and then go back to “Today”, the date is now part of the URL query string. It looks similar to:
https://plausible.io/YOURSITE.COM?period=day&keybindHint=D&date=2024-10-30
If I come back tomorrow, and just reload the page (not realizing it has yesterday’s date in the query string) it will show yesterday’s stats. It may not be everyone’s workflow to start at the site list (https://plausible.io/sites), and instead users may want to stay on a single site most of the time (especially if they only have plausible analytics collection configured for a single site.)
If the date was not in the URL query string, reloading the site page after 24 hours or more goes by would not display that specific day’s stats but instead reveal today’s stats, which is probably what the user was looking for anyway.
In short, clicking on “Today” should show today’s stats without the date in the URL query string, and then when tomorrow rolls around, reloading the site page should show the current day’s stats.